Methods for quantifying environmental health impacts

Exposure-based methods

This method to calculate the environmental burden of disease is based on an exposure approach, supported by a comprehensive analysis of the evidence for the given health risks.

Exposure-response relationships for a given risk factor are obtained from epidemiological studies and the derived attributable fractions are then applied to disease burden, expressed in deaths or DALYs, associated with the risk factor.

For six environmental risk factors and five occupational risk factors, a detailed analysis is provided in the reference publication (Comparative Quantification of Health Risks) below.

In addition, a more detailed analysis and step-by-step approach for the different risk factors is provided in the Environmental burden of disease Series (EBD Series). The first volume provides a excellent introduction and a summary of the basic methodology for quantifying environmental health impacts at national and local levels.

Expert opinion method

Urban environments conducive to physical activity

Sudipto Das/WHO

In a report published in 2006, "Preventing disease through healthy environments: towards an estimate of the global burden of disease", WHO presented estimations of how much of global disease could be prevented by modifying the environment.

This work builds on the previous efforts that WHO has undertaken to quantify the global estimates of burden of disease caused by 26 risk factors, published in the World Health Report 2002 (and whose method is described in the above-mentioned reference publication), and involves a systematic review of literature as well as surveys of over 100 experts worldwide. The report gives, for 85 out of the 102 major diseases and injuries classified by WHO, the fraction of disease that can be attributed to the environment and that could be prevented. These environmental contributions are sometimes available by regions, by economic status (high/low income countries), by age group or by gender, depending on the available data and the domain of expertise of the experts.